Approaching Conjunction

Jupiter & Saturn

In Brief

JupiterSaturn
Magnitude: -2.0+0.6
Apparent diameter (arc-sec):34.2″15.6″
Equatorial Diameter (km):142,984120,536
Distance from Earth (light minutes): 47.9688.58

All eyes are on the Western sky for the next six weeks as Jupiter and Saturn edge slowly towards each other. When I took this image last night, the apparent gap between the two planets had narrowed to 1° 54′ and both of them fitted very comfortably inside the field of view of my 200mm camera lens.

In a few days time they will fit into my telescope field of view. That’s if the clouds disperse – and I don’t have much confidence about that!

By 21st December the gap between the two will be as narrow as 6.5 arc-minutes.

Here is a table of the angular separation distances (in arc-minutes) during this approach, as seen in the early evening here in Sydney:

NARROWING
MonthDecDecDecDecDecDecDecDecDec
Day579111315171921
Separation108′95′82′69′60′43′30′17′6.5′
WIDENING
MonthDecDecDecDecDecJanJanJan
Day2325272931246
Separation13′25′38′52′65′79′93′107′

To add to the attraction, between 7th and 14th January the planet Mercury will whiz closely past Jupiter and Saturn at a relatively fast rate. It will be at magnitude -0.9, (midway in brightness between Jupiter and Saturn). I’ll be trying to spot this event, although it will be very low in the sky.

On the 10th January, Mercury will form a close triangle with Jupiter and Saturn – and four days later a young crescent Moon will also be in close attendance. However, a clear Western horizon view will be essential because by that time the planetary conjunction will be only just above the horizon immediately after sunset.

14th January 2021
Saturn, Jupiter, Mercury and the Moon.
Image derived from Cartes du Ciel

Cameras at the ready!

Details of Feature Image

Image date: 2020-12-04
Exposure: 200mm lens, 1/30 sec, f/2.8, ISO640
Imaging camera: Canon EOS 6oD
Software processing: DPP & Gimp.
Observatory location: 34° South.

Images © Roger Powell

I’m a founder member of Macarthur Astronomical Society

18 Comments

      1. So, today:
        5 pm: Jupiter at 23° apparent
        6 pm: Jupiter at 16° apparent

        16° is too low unless I can find a spot somewhere else. Probably doable somewhere but my issue is that nearly all the roads here have obstructions. There are a couple of lakes that might offer viewing spots, but even there, the alignment of road to lake is not favorable. For me, it’s more of a SW direction, approaching halfway between SW and W by the time it sinks below the horizon. West would be great because there are a couple of places where I’d look right over a lot of water and should be able to see lower than 16°.

        On the 21th:
        5 pm: Jupiter at 19° apparent
        6 pm: Jupiter at 10° apparent

        I’m rounding numbers, but that makes it even more difficult. However, if it’s clear, I should be able to see them before 5pm (sunset at 4:36)

        On the January 10th:
        5:15 pm: Saturn at 5° apparent
        6 pm: Jupiter at 0° apparent

        That last group is when Stellarium says Saturn (the last of the three) becomes visible. They are probably optimistic, but even so that’s much lower than I can see anywhere, even without the likelihood of clouds on the horizon. This would have been easier in Hawaii . . . except that very few times did we see a true sunset (sun melting into the water). Usually, it would disappear behind clouds that were not visible until the sun set behind them.

        However, on the 18th, at 5:40 pm local time, IGS5AR is supposed to pass right between Jupiter and Saturn . . . that, I’m going to try to see. It will be at the edge of visibility, but I’ll give it a shot if it’s not overcast.

        Liked by 2 people

        1. It will be challenging for anyone in suburbia, as the planets head towards the horizon. If only my neighbours had not planted those trees…..

          If circumstances were normal I would be out at some vantage point with my friends. I have a partially obstructed Western view and I am not sure how much I will see, even if I get a cloud free night.

          Hence I started seventeen days early.

          Like

      2. Oh, one more . . . tonight, 5:31:54 local time, Kosmos 482 will pass very close to the Saturn/Jupiter pair. I might try my hand at photographing it. It’s been a while since I pointed the camera at the night sky, so I might miss it without some practice.

        Hubble will pass by them at 6:03, but by then, they’ll be too low unless I go find a better spot.

        One of my prior efforts in a much better sky (Colorado on a clear night):
        This is a not-so-good picture looking roughly West from my deck.  This is the evening of March 13, 2012.

        Use the “>” symbol on the right to navigate the gallery. Click anywhere to enlarge.

        Each photo is annotated and I identify a few things like the IC 349 nebula and I even get NGC 1981 as a pink/purple smudge.

        I really should get back to doing some astro photography (even with my limited equipment). I might get some readers interested in looking up from their twitter and facebook accounts.

        Liked by 2 people

          1. Eh, not sure I learned the trade . . . I failed to see COSMOS 482. It turns out the magnitude setting wasn’t on in Stellarium. However, tomorrow night at 17:13:40, it’s supposed to pass between Saturn and Jupiter at a magnitude -5.2.

            Still too dim for my eyes for where I am, but maybe not for the camera. We’ll see.

            Liked by 1 person

            1. A mag -5.2 star might show up easily in a wide field long exposure. A moving satellite will appear much dimmer on the image but it’s hard to judge and it’s worth a go. You may need to over-expose the planets.

              Liked by 1 person

            2. I’m planning on relying on a 3″ exposure (transition time between planets) at a high ISO 2k-3K and to clean up the noise in post.

              The planets will be overexposed, but I’m hoping to see the streak of the space junk between the planets. We’ll see if I can execute it. It’s still in twilight, so I’m not sure I’ll get anything at all.

              Liked by 1 person

  1. Thanks for your in depth and extremely informative post of this up-coming event. I’ve been encouraging our grown children to check this one out with their kids, sending them info and hints of where to be and how to view the event on and about the 21st. M 🙂

    Liked by 1 person

  2. I’ve been fortunate to have clear evening skies about every 5th day since early November. Monday looks to be another. My composite of the closing distance is looking good. I’ll share again soon.

    This evening, my wife and I went out about 5:30 and watched nearly 60 Starlink satellites pass overhead and near Mars. I set the camera to record, if possible. This short one showed 5 passing in the upper left corner of the frame. https://youtu.be/laEJ1sQdCDw

    Liked by 1 person

    1. Thanks for posting that interesting video.

      I’m not a fan of Starlink satellites. They seem to mark the beginning of a new space era where satellites which are put into Earth orbit for essential scientific reasons by national governments are now going to be swamped by non-essential satellites put up there to make a tidy profit for private enterprise and the billionaires who own them. There are no laws for them to comply with.

      I hope you get a few more clear views of the conjunction.

      Liked by 1 person

      1. I agree about the Starlinks. It seems we could have a solution to remote sites having internet access without so many things flying over. They are fascinating to watch. We were kind of spellbound for about 3 minutes.

        Liked by 1 person

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